Stabilized, Sprayable Emulsion Containing Active Agent Particles

ABSTRACT

A sprayable emulsion is provided. The emulsion can be used in the treatment of various skin conditions. The emulsion includes a hydrofluoro-based propellant, an emulsification system, an oil phase, a water phase, and active agent particles. Further, the emulsification system includes at least one nonionic emulsifier. The emulsion has a viscosity ranging from about 500 centipoise to about 10,000 centipoise and a hydrophilic to lipophilic balance (HLB) value of from about 2 to about 12. The present inventors have found that by selectively controlling the nature of the emulsification system and the viscosity of the emulsion, the active agent particles resist settling such that a substantially homogeneous distribution of the active agent particles is maintained and can be evenly sprayed onto a surface without running once applied.

RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationSer. No. 61/939,829, filed on Feb. 14, 2014, which is incorporatedherein in its entirety by reference thereto.

BACKGROUND OF THE INVENTION

Much of the population has experienced a skin condition such as a rash,a pressure ulcer, a wound such as a cut or first degree burn, anallergic reaction, or any other skin condition that can cause itching,inflammation, pain, or any other type of discomfort that has requiredtopical application of a cream or ointment to assist in the healingprocess. Often, some of these conditions are more prevalent in infants,the elderly, and infirm. For instance, infants, the elderly, and infirmcan be susceptible to developing incontinent dermatitis, which occurswhen the skin is exposed to prolonged wetness, increased skin pH causeddue to contact with urine and feces, and the resulting breakdown of thestratum corneum, or the outermost layer of the skin. Meanwhile, pressureulcers, also known as decubitus ulcers or bedsores, are also a concern.Pressure ulcers are localized injuries to the skin and/or underlyingtissue that usually occur over a bony prominence as a result ofpressure, or pressure in combination with shear and/or friction. Themost common sites are the sacrum, coccyx, heels or the hips, but othersites such as the elbows, knees, ankles or the back of the cranium canbe affected. Pressure ulcers occur due to pressure applied to softtissue resulting in completely or partially obstructed blood flow to thesoft tissue. Factors that can contribute to the formation of ulcersinclude protein-calorie malnutrition, microclimate (skin wetness causedby sweating or incontinence), diseases that reduce blood flow to theskin, such as arteriosclerosis, or diseases that reduce the sensation inthe skin, such as paralysis or neuropathy.

The aforementioned conditions, and other skin conditions, can beprevented or treated, for instance, by the application of an activeagent to the affected area of the skin. Active agents can, for instance,help speed up the wound healing process and can also limit the skin'sexposure to excessive moisture. As such, one approach for treating theseskin conditions is to block moisture from reaching the skin, such as bythe application of oil-based protectants or barrier creams, includingvarious over-the-counter creams or ointments containing moisture barrieractive agents, to the affected area. However, if the skin is notthoroughly dry, some of these oil-based protectants and creams canactually seal the moisture inside the skin rather than outside the skin.Further, such protectants and creams are very viscous and can be greasy,resulting in difficulty in removing the protectants and creams fromone's hands after application onto the affected area of the skin. Inaddition, rubbing these products into the skin can cause additionaldiscomfort or pain, and in the event that a caretaker or healthcareprovider must apply the product to a patient, this could lead toembarrassment for both the patient and caretaker depending on thelocation of application.

As such, a need exists for a composition that can provide an evencoating of an active agent to the skin that is easier to apply and thatdoes not cause discomfort. One approach is to use an active agent inconjunction with a propellant to create a sprayable composition.However, often the high viscosity of the resulting aerosol spraycomposition means that it can be difficult to formulate the compositioninto a medium that can be sprayed due to issues with clogging of thevalves and nozzle in the dispenser. Meanwhile, to counteract thisproblem, other sprayable compositions are formulated to have a lowviscosity to allow for spraying, but this can result in compositionsthat are not viscous enough when applied to the skin's surface,resulting in a runny product that does not evenly coat or effectivelycontact the skin.

Still another problem associated with the aforementioned sprayablecompositions is that the active agents of the sprayable compositions areparticulate-based and often settle to the bottom of the container inwhich the sprayable composition is stored, particularly when theviscosity is low, resulting in caking of the product in the containerand the inability to deliver the active agent in a uniform manner.

As such, a need exists for a stable, sprayable composition containingactive agent particles that remain substantially homogeneouslydistributed and that can be evenly sprayed onto the skin as a fine mist.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a sprayableemulsion is disclosed. The emulsion includes a hydrofluoro-basedpropellant, an emulsification system, an oil phase, a water phase, andactive agent particles. Further, the emulsification system includes atleast one nonionic emulsifier. The sprayable emulsion has a viscosityranging from about 500 centipoise to about 10,000 centipoise and ahydrophilic to lipophilic balance (HLB) value of from about 2 to about12.

In accordance with another embodiment of the present invention, a methodof forming a sprayable emulsion is disclosed. The method includesforming a base emulsion composition, introducing the base emulsioncomposition into a spray container, and injecting a hydrofluoro-basedpropellant into the container. The base emulsion composition includesactive agent particles, an emulsification system, an oil phase, and awater phase. Further, the emulsification system includes at least onenonionic emulsifier. In addition, the sprayable emulsion has a viscosityof from about 500 centipoise to about 10,000 centipoise and ahydrophilic to lipophilic balance (HLB) value of from about 2 to about12.

Other features and aspects of the present invention are set forth ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figure, in which:

FIG. 1 is a cross-sectional side view of a spray delivery systemaccording to one embodiment of the present disclosure;

FIG. 2A is front view of an actuator that can be used in a spraydelivery system according to one embodiment of the present disclosure;

FIG. 2B is a cross-sectional side view of the actuator of FIG. 2A;

FIG. 3 is a cross-sectional side view of a spray assembly according toone embodiment of the present disclosure; and

FIG. 4 is a cross-sectional side view of a spray delivery systemaccording to another embodiment of the present disclosure utilizing thespray assembly of FIG. 3.

Repeat use of reference characters in the present specification anddrawing is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention.

Generally speaking, the present invention is directed to a sprayableemulsion that can be used, for example, in the treatment of a skincondition or any other condition where the topical application of anactive composition is desired. The emulsion can be used in the treatmentof various skin conditions. The emulsion includes a hydrofluoro-basedpropellant, an emulsification system, an oil phase, a water phase, andactive agent particles. Further, the emulsification system includes atleast one nonionic emulsifier. The present inventors have found that byselectively controlling the type of propellant used, the nature of theemulsification system, and the viscosity of the emulsion, a sprayableemulsion can be achieved where the active agent particles resistsettling such that a substantially homogeneous distribution of theactive agent particles is maintained and can be evenly sprayed onto asurface without running once applied. For instance, the sprayableemulsion can be stable such that less than about 3 wt. %, such as lessthan about 2 wt. %, such as less than about 1 wt. % of the active agentparticles in the emulsion settle when stored in a container at 21° C.for 3 days. This results in an emulsion that can be evenly sprayed on asurface as a substantially uniform coating of active agent particles. Inaddition, the emulsion can have a viscosity ranging from about 500centipoise to about 10,000 centipoise, such as from about 1000centipoise to about 8000 centipoise, such as from about 1500 centipoiseto about 6000 centipoise, such as from about 2000 centipoise to about4000 centipoise.

The propellant can be, for instance, a hydrofluoro-based propellant suchas a hydrofluoro-olefin or a hydrofluoroalkane. Further, theemulsification system can include at least one nonionic emulsifier. Insome embodiments, one or more nonionic lipophilic emulsifiers can beused in conjunction with one or more nonionic hydrophilic emulsifierssuch that the ratio of the hydrophilic/lipophilic balance (“HLB”) valueof the overall sprayable emulsion can range from about 2 to about 12,such as from about 3 to about 10, such as from about 4 to about 9, suchas from about 5 to about 8. Meanwhile, the ratio of the lipophilicemulsifiers to the hydrophilic emulsifiers used can range from about 5to about 30, such as from about 7.5 to about 25, such as from about 10to about 20.

I. Sprayable Emulsion

a. Propellant

The sprayable emulsion of the present invention includes a propellant toprovide the energy needed to aid in the delivery of active agentparticles to a surface of the skin affected with skin conditions such asrashes, ulcers, cuts, or wounds. In other words, the propellant canprovide the propulsive forced needed to spray the active agent particlesonto the skin. As such, the propellant has enough dispersive energy toovercome the surface tension of the liquid components of the sprayableemulsion.

The emulsion includes a propellant particularly useful for facilitatingthe spray of the active agent particles. The present inventors havefound that by selectively controlling certain aspects of the propellant,such as the specific gravity, vapor pressure, and/or molecular weight, acomposition having a substantially homogeneous distribution of activeagent particles can be achieved.

The ratio of the specific gravity of the propellant to specific gravityof the emulsion can range from about 0.7 to about 1.6, such as fromabout 0.8 to about 1.5, such as from about 0.9 to about 1.4. Such aspecific gravity ratio results in the propellant having a specificgravity similar to the overall emulsion, which means that the propellantcan be substantially homogeneously distributed throughout the emulsion.Because the propellant is distributed throughout the emulsion in thismanner, settling of the active agent particles and other particulatescontained in the sprayable emulsion can be prevented. Further, thepropellant can have a specific gravity ranging from about 1.03 to about1.3, such as from about 1.05 to about 1.25, such as from about 1.07 toabout 1.2 as determined at 21° C. and based on water having a density of1.0 at 21° C. Meanwhile, the sprayable emulsion can have a specificgravity of from about 0.8 to about 1.3, such as from about 0.85 to about1.25, such as from about 0.9 to about 1.2, as determined at 21° C.

In addition, the propellant can provide a high enough vapor pressure tothe emulsion such that it can be atomized and sprayed in aerosol form,yet the vapor pressure is not so high that the resulting spray createsexcessive misting or discomfort when sprayed onto the skin or requires aspecially designed aerosol container. For instance, the vapor pressureat room temperature (21° C.) can be less than about 60 psi. In someembodiments, for example, the vapor pressure can range from about 30 psito about 60 psi, such as from about 35 psi to about 55 psi, such as fromabout 40 psi to about 50 psi. Without intending to be limited by theory,it is believed that by using a propellant that has a lower vaporpressure at room temperature compared to other propellants, thepropellant can be used in larger amounts in the sprayable emulsion,which results in a smoother, more easily controlled, spray and alsoensures complete evacuation of the container in which the sprayableemulsion is stored. Further, because the propellant's low vaporpressure, it is not necessary to use a high pressure aerosol containeras is required when utilizing other propellants.

In addition, the molecular weight of the propellant can be greater than100 grams per mole, such as from about 100 grams per mole to about 400grams per mole, such as from about 105 grams per mole to about 300 gramsper mole, such as from about 110 grams per mole to about 200 grams permole. By using a propellant having a molecular weight in this range,settling of the active agent particles can be further prevented.

In one embodiment, the propellant can include at least onehydrofluoro-olefin. In one particular embodiment, the propellantincludes a hydrofluoro-olefin containing from 3 to 4 carbon atoms, suchas three carbon atoms. The hydrofluoro-olefin propellant of the presentinvention can be referred to as an “HFO” when it contains at least onehydrogen, at least one fluorine and no chlorine. HFOs are derivatives ofalkenes. In some embodiments, the HFO propellant can contain twocarbon-carbon double bonds.

In one particular embodiment, the sprayable emulsion of the presentinvention includes a propellant represented by Formula I below:

where each R is independently a hydrogen or a halogen such as fluorine(F), bromine (Br), iodine (I), or chlorine (Cl), and preferably fluorine(F),

R′ is (CR₂)_(n)Y,

Y is CRF₂, and

n is 0 or 1.

Further, in one particular embodiment, Y is CF₃, n is 0, and at leastone of the remaining Rs is F. In another particular embodiment, Y isCF₃, at least one R on the unsaturated terminal carbon is H, and atleast one of the remaining Rs is F. In still other embodiments, thefluoro-olefin propellant of the present invention can include one ormore tetrafluoropropenes, and such a propellant can be referred toherein as a HFO-1234 propellant. Examples of tetrafluoropropenescontemplated by the present invention are HFO-1234yf (specific gravityof 1.092 at 21° C.) and HFO-1234ze (specific gravity of 1.17 at 21° C.),in the cis- and/or trans-forms. It should be understood that HFO-1234zerefers to 1,1,1,3-tetrafluoropropene, independent of whether it is thecis- or trans-form, and the terms “cisHFO-1234ze” and “transHFO-1234ze”are used herein to describe the cis- and trans-forms of1,1,1,3-tetrafluoropropene, respectively.

In some embodiments, the HFO-1234ze can include a combination oftransHFO-1234ze and cisHFO-1234ze, such as from about 90% to about 99%trans-isomer on the basis of total HFO-1234ze, with the cis-isomercomprising from about 1% to about 10% of the same basis. As such, insome embodiments, the propellant of the present invention can include acombination of cisHFO-1234ze and transHFO-1234ze, preferably in a cis-to trans-weight ratio of from about 1:99 to about 10:99, such as fromabout 1:99 to about 5:95, such as from about 1:99 to about 3:97.

Although the properties of cisHFO-1234ze and transHFO-1234ze differ inat least some respects, it is contemplated that each of these compoundsis adaptable for use, either alone or together with other compoundsincluding its stereoisomer, as a propellant in the sprayable emulsion ofthe present invention. For example, while transHFO-1234ze has arelatively low boiling point (−19° C.), it is nevertheless contemplatedthat cisHFO-1234ze, with a boiling point of 9° C., can also be used as apropellant in the sprayable emulsion of the present invention. Further,it is to be understood that the terms HFO-1234ze and1,1,1,3-tetrafluoropropene refer to both stereo isomers, and the use ofthese terms covers both the cis- and trans-forms.

Another type of propellant that can be used is a hydrofluoroalkane,which can be referred to as an “HFA.” HFA propellants are also known ashydrofluorocarbons or “HFC” propellants. An example of a suitable HFCpropellant is 1,1,1,2-tetrafluoroethane, which can also be referred toas HFC-134a. Another type of HFC propellant that can be used is1,1,1,2,3,3,3-heptafluoropropane, which can also be referred to asHFC-227ea.

Regardless of the particular propellant utilized, the amount of thepropellant contained in the sprayable emulsion of the present inventioncan range from about 5 wt. % to about 95 wt. %, such as from 10 wt. % toabout 80 wt. %, such as from about 15 wt. % to about 60 wt. % based onthe total weight of the emulsion.

b. Active Agent Particles

The sprayable emulsion of the present invention further includes activeagent particles, which can mean any compound or mixture of compoundswhich produces a physiological result upon contact with a livingorganism (e.g., a mammal) such as a human. Active agent particles can bedistinguishable from other components of the sprayable emulsion, such aspreservatives, conditioning agents, emollients, viscosity modifiers,emulsifiers, etc. The active agent particles can include any molecule,as well as a binding portion or fragment thereof, that is capable ofmodulating a biological process. In some embodiments, the active agentparticles can be used in the diagnosis, treatment, or prevention of adisease or as a component of a medication, pharmaceutical, cosmetic, orcosmeceutical. Further, the active agent particles can be compounds thatinteract with or influence or otherwise modulate a target in a livingsubject. The target may be a number of different types of naturallyoccurring structures, where targets of interest include bothintracellular and extra-cellular targets. Active agent particles caninclude, for example, moisture barriers, antifungals, antibacterials,analgesics, antiseptics, anesthetics, anti-inflammatories,antipruritics, etc. The active agent particles can have an averageparticle size of from about 20 nanometers to about 1000 nanometers, suchas from about 25 nanometers to about 500 nanometers, such as from about30 nanometers to about 250 nanometers.

In one embodiment, the active agent particles can include zinc oxideparticles, which repel moisture and create a barrier between the skinand environment to protect the skin from excessive moisture. The zincoxide particles can have an average particle size of from about 20nanometers to about 200 nanometers, such as from about 25 nanometers toabout 150 nanometers, such as from about 30 nanometers to about 100nanometers.

The zinc oxide particles can be hydrophobic, for example, by applicationof a hydrophobic coating on the surface of the zinc oxide particles, asdescribed in more detail below. The particles can also carry aninorganic coating, separately or in combination with the hydrophobiccoating, as described in more detail below. The zinc oxide particles maybe coated with alumina, silica, an organic material, silicones, orcombinations thereof. Other suitable surface treatments may include:phosphate esters (including lecithins), perfluoroalkyl alcoholphosphates, fluorosilanes, isopropyl titanium triisostearate, stearic orother fatty acids, silanes, dimethicone and related silicone polymers,or combinations thereof.

For example, zinc oxide particles may be coated with oxides of otherelements such as oxides of aluminum, zirconium or silicon, or mixturesthereof such as alumina and silica. Alternatively, the zinc oxideparticles may be treated with boron nitride or other known inorganiccoatings, singly or in combinations before incorporation into the voidsof the particulate. The inorganic coating may be applied usingtechniques known in the art. A typical process can include forming anaqueous dispersion of zinc oxide particles in the presence of a solublesalt of the inorganic element whose oxide will form the coating. Thisdispersion is usually acidic or basic, depending upon the nature of thesalt chosen, and precipitation of the inorganic oxide is achieved byadjusting the pH of the dispersion by the addition of acid or alkali, asappropriate. The inorganic coating, if present, can be applied as afirst layer to the surface of the zinc oxide particles.

In another embodiment, the zinc oxide particles can include an organiccoating that provides hydrophobicity. The organic coating can be appliedto the inorganic coating, if present, or directly to the zinc oxide. Thehydrophobic coating agent may be, for example, a silicone, a silane, ametal soap, a titanate, an organic wax, or combinations thereof. Thehydrophobic coating can alternatively include a fatty acid, for example,a fatty acid containing 10 to 20 carbon atoms, such as lauric acid,stearic acid, isostearic acid, and salts of these fatty acids. The fattyacid may be isopropyl titanium trisostearate. With respect to thesilicone, the hydrophobic coating may be a methicone, a dimethicone,their copolymers or mixtures thereof. The silicone may also be anorganosilicon compound, for example dimethylpolysiloxanes having abackbone of repeating —Me₂SiO— units (“Me” is methyl, CH₃), methylhydrogen polysiloxanes having a backbone of repeating —MeHSiO— units andalkoxysilanes of formula R_(n)OSiH_((4-n)) where “R” is alkyl and “n” isthe integer 1, 2 or 3. With respect to the silane, the hydrophobiccoating agent may be an alkoxysilanes, for example an alkyltriethoxy oran alkyltrimethoxy silanes available from OSI Specialties or PCR. Thealkoxysilane may be a triethoxycaprylylsilane or a perfluoroalkylethyltriethoxysilane having a C₃ to C₁₂ alkyl group that is straight orbranched. Zinc oxide particles with a triethoxycaprylylsilane coatingare commercially available under the name ZANO™ 10 Plus from UmicoreZinc Chemicals.

Still other active agent particles that can be used in the sprayableemulsion can include paraffin, microcrystalline wax, petrolatum,beeswax, or a combination thereof. Such active agent particles can actas moisture repellant materials.

Regardless of the type of active agent particles utilized, the amount ofactive agent particles contained in the sprayable emulsion of thepresent invention can range from about 0.1 wt. % to about 30 wt. %, suchas from 1 wt. % to about 25 wt. %, such as from about 2 wt. % to about20 wt. % based on the total weight of the emulsion.

c. Oil and Water Phases

The sprayable emulsion can also include an oil phase and a water phase.The oil phase and the water phase can form a water-in-oil emulsion or anoil-in-water emulsion. Suitable oils that can be used in the oil phaseof the emulsion include mineral oils, plant-based oils, silicone oils,or a combination thereof. Examples of commercially available mineraloils, which are liquid petroleum derivatives that may be used inaccordance with the present invention can include Witco Corporation'sCARNATION™ mineral oil or Penreco Corporation's DRAKEOL™ mineral oil.Suitable plant-based oils, which are non-petroleum biomass derived oils,that can be used include vegetable or fruit oils, such as almond oil,peanut oil, wheat germ oil, linseed oil, jojoba oil, apricot pit oil,walnut oil, palm nut oil, pistachio nut oil, sesame seed oil, rapeseedoil, cade oil, corn oil, peach pit oil, poppy seed oil, pine oil, castoroil, soybean oil, avocado oil, safflower oil, coconut oil, hazelnut oil,olive oil, grape seed oil, sunflower oil, apricot kernel oil, geraniumoil, rice bran oil and mixtures thereof. Silicone oils that can be usedinclude disiloxane, cyclomethicone, dimethicone and derivatives thereof,and polydimethylsiloxane fluids. Cyclomethicone is a volatile compoundand evaporates when applied to the skin's surface, such that theresulting coating is drier to the touch. Other similar volatilecompounds that can be used include isododecane.

Water can be used in conjunction with any of the oils described above aspart of water phase of a water-in-oil emulsion or an oil-in-wateremulsion. The water phase can include water alone, or the water phasecan include water in addition to one or more water soluble components ofthe sprayable emulsion.

When an emulsion containing oil and water is formed, the oil can bepresent in the emulsion in an amount ranging from about 1 wt. % to about35 wt. %, such as from about 3 wt. % to about 30 wt. %, such as fromabout 5 wt. % to about 25 wt. % based on the total weight of theemulsion. Meanwhile, the water can be present in an amount less thanabout 50 wt. %, such as an amount ranging from about 1 wt. % to about 50wt. %, such as from about 5 wt. % to about 45 wt. %, such as from about10 wt. % to about 40 wt. % based on the total weight of the emulsion.Further, the total amount of the oil and water phases present in theemulsion can range from about 10 wt. % to about 70 wt. %, such as fromabout 15 wt. % to about 65 wt. %, such as from about 20 wt. % to about60 wt. % based on the total weight of the emulsion.

d. Emulsification System

The sprayable emulsion also includes an emulsification system. Theemulsification system can include one or more emulsifiers to help createa stable, substantially homogeneous, uniform dispersion of thepropellant and the active agent particles by preventing the separationof the sprayable emulsion into constituent phases. The emulsificationsystem may include one or more nonionic, anionic, and/or amphotericemulsifiers, including mixtures containing different species or mixturesof different surfactants within the same species. In one particularembodiment, the emulsification system includes one or more nonionicemulsifiers.

Nonionic surfactants, which typically have a hydrophobic base (e.g.,long chain alkyl group or an alkylated aryl group) and a hydrophilicchain (e.g., chain containing ethoxy and/or propoxy moieties), can beparticularly suitable. Some suitable nonionic surfactants that may beused include, but are not limited to, ethoxylated alkylphenols,ethoxylated and propoxylated fatty alcohols, polyethylene glycol ethersof methyl glucose, polyethylene glycol ethers of sorbitol, ethyleneoxide-propylene oxide block copolymers, ethoxylated esters of fatty(C₈-C₁₈) acids, condensation products of ethylene oxide with long chainamines or amides, condensation products of ethylene oxide with alcohols,fatty acid esters, monoglycerides, or diglycerides of long chainalcohols, and mixtures thereof. Particularly suitable nonionicemulsifiers may include ethylene oxide condensates of fatty alcohols(e.g., sold under the trade name Lubrol), polyoxyethylene ethers offatty acids (particularly C₁₂-C₂₀ fatty acids), polyoxyethylene sorbitanfatty acid esters (e.g., sold under the trade name TWEEN®), and sorbitanfatty acid esters (e.g., sold under the trade name SPAN™ or ARLACEL®),etc. The fatty components used to form such emulsifiers may be saturatedor unsaturated, substituted or unsubstituted, and may contain from 6 to22 carbon atoms, in some embodiments from 8 to 18 carbon atoms, and insome embodiments, from 12 to 14 carbon atoms.

Although any emulsifier may generally be employed, the present inventorshave discovered that a certain combination of hydrophilic and lipophilicnonionic emulsifiers is particularly effective in stabilizing theemulsion. As is known in the art, the relative hydrophilicity orlipophilicity of an emulsifier can be characterized by thehydrophilic/lipophilic balance (“HLB”) scale, which measures the balancebetween the hydrophilic and lipophilic solution tendencies of acompound. The HLB scale ranges from 0.5 to approximately 20, with thelower numbers representing highly lipophilic tendencies and the highernumbers representing highly hydrophilic tendencies. Desirably, theemulsion of the present invention can include at least one “hydrophilic”emulsifier that has an HLB value of from about 10 to about 20, in someembodiments from about 12 to about 19, and in some embodiments, fromabout 14 to about 18. Likewise, the emulsion can also include at leastone “lipophilic” emulsifier that has an HLB value of from about 0.5 toabout 10, in some embodiments from about 1 to about 9, and in someembodiments, from about 2 to about 8. If desired, two or moresurfactants may be employed that have HLB values either below or abovethe desired value, but together have an average HLB value within thedesired range. Regardless, the present inventors have discovered thatthe weight ratio of lipophilic emulsifiers to hydrophilic emulsifiers inthe sprayable emulsion is typically within a range of from about 5 toabout 30, in some embodiments from about 7.5 to about 25, and in someembodiments, from about 10 to about 20. Further, the present inventorshave discovered that the overall HLB value of the sprayable emulsion isgenerally lipophilic and ranges from about 2 to about 12, such as fromabout 3 to about 10, such as from about 4 to about 9, such as from about5 to about 8.

One particularly useful group of “lipophilic” emulsifiers are sorbitanfatty acid esters (e.g., monoesters, diester, triesters, etc.) preparedby the dehydration of sorbitol to give 1,4-sorbitan, which is thenreacted with one or more equivalents of a fatty acid. The fatty-acidsubstituted moiety can be further reacted with ethylene oxide to give asecond group of surfactants. The fatty-acid-substituted sorbitansurfactants are made by reacting 1,4-sorbitan with a fatty acid such aslauric acid, palmitic acid, stearic acid, oleic acid, or a similar longchain fatty acid to give the 1,4-sorbitan mono-ester, 1,g-sorbitansesquiester or 1,4-sorbitan triester. The common names for thesesurfactants include, for example, sorbitan monolaurate, sorbitanmonopalmitate, sorbitan monoestearate, sorbitan monooleate, sorbitansesquioleate, and sorbitan trioleate. Such surfactants are commerciallyavailable under the name SPAN™ or ARLACEL™, usually with a letter ornumber designation which distinguishes between the various mono-, di-and triester substituted sorbitans. SPAN™ and ARLACEL™ surfactants arelipophilic and are generally soluble or dispersible in oil, but notgenerally soluble in water. One particularly suitable surfactant issorbitan oleate, which is commercially available as SPAN™ 80. Generallythese surfactants will have HLB value in the range of 1.8 to 8.6.

Other useful lipophilic emulsifiers that can be used can include, forexample, silicone water-in-oil emulsifiers. By silicone it is meant amolecule that includes at least one siloxane (—Si—O—) repeating unit andfurther includes a hydrophobic moiety and a hydrophilic moiety. The HLBvalue of the silicone water-in-oil emulsifier is relatively low. Forexample, in some embodiments, the silicone emulsifier can have an HLBvalue in the range of 2 to 9.

Examples of suitable silicone water-in-oil emulsifiers can includenon-crosslinked dimethicone copolyols such as alkoxy dimethiconecopolyols, silicones having pendant hydrophilic moieties such as linearsilicones having pendant polyether groups, branched polyether and alkylmodified silicones, branched polyglycerin and alkyl modified silicones,and combinations thereof. Examples of commercially availablenon-crosslinked dimethicone copolyols include the following from DowCorning of Midland, Mich.: cyclopentasiloxane and PEG/PPG-18/18dimethicone available as DC 5225C, and cyclopentasiloxane and PEG-12dimethicone crosspolymer available as DC9011. Certain non-crosslinkeddimethicone copolyols are cetyl dimethicone copolyols such as cetylPEG/PPG-10/1 dimethicone sold under the name ABIL™ EM-90, branchedpolyether and alkyl modified silicones such as lauryl PEG-9polydimethylsiloxyethyl dimethicone sold under the name KF-6038, andbranched polyglycerin and alkyl modified silicones such as laurylpolyglyceryl-3 polydimethylsiloxyethyl dimethicone sold under the nameKF-6105. Other non-crosslinked dimethicone copolyols include, forexample, bis-PEG/PPG-14/dimethicone copolyol sold under the name ABIL™EM-97 and the polyglyceryl-4 isostearate/cetyl dimethiconecopolyol/hexyl laurate mixture sold under the name ABIL™ WE 09. ABIL™EM-90, ABIL™ EM-97, and ABIL™ WE 09 are available from EvonikGoldschmidt GmbH of Essen, Germany. KF-6038 are KF-6105 are availablefrom Shin-Etsu Silicones of Akron, Ohio. One particularly suitableemulsifier for use in the present invention is ABIL™ WE 09, which has anHLB value of about 5. Another particularly suitable emulsifier is ABIL™EM 90, which also has an HLB value of about 5.

Still another suitable nonionic lipophilic emulsifier that can beincluded in the sprayable emulsion of the present invention isoctyldodecanol/octyldechyl xyloside/PEG-30, which is commerciallyavailable from Seppic S.A. under the name EASYNOV™.

Meanwhile, sorbitan fatty acid esters (e.g., monoesters, diester,triesters, etc.) that have been modified with polyoxyethylene arelikewise a particularly useful group of “hydrophilic” emulsifiers. Thesematerials are typically prepared through the addition of ethylene oxideto a 1,4-sorbitan ester. The addition of polyoxyethylene converts thelipophilic sorbitan ester surfactant to a hydrophilic surfactant that isgenerally soluble or dispersible in water. Such materials arecommercially available under the designation TWEEN™ (e.g., TWEEN™ 80,polysorbate 80, or polyethylene (20) sorbitan monooleate). TWEEN™surfactants generally have a HLB value in the range of 9.6 to 16.7. Forinstance TWEEN™ 80 has an HLB value of 15. Still other suitablehydrophilic emulsifiers can include sucrose fatty acid esters, such assaccharose monopalmitate (HLB of 15) and saccharose monostearate (HLB of11), or PEG-32 glyceryl laurate (HLB of 14), as well as polyethyleneglycol (PEG) n-alkanol esters of the BRIJ™ family such as BRIJ™ 35, 56,58, 76, 78, and 99, which have an HLB in the range of 12.4 to 16.9.BRIJ™ 56 is polyoxyethylene[10] cetyl ether, for example, has an HLBvalue of 12.9.

Regardless of the particular emulsifiers utilized in the emulsificationsystem, the emulsification system can be present in the sprayableemulsion in an amount ranging from about 0.1 wt. % to about 20 wt. %,such as from about 0.5 wt. % to about 15 wt. %, such as from about 1 wt.% to about 10 wt. % based on the total weight of the emulsion. Further,the present inventors have discovered that the weight ratio oflipophilic emulsifiers to hydrophilic emulsifiers in the emulsificationsystem component of the sprayable emulsion is typically within a rangeof from about 5 to about 30, in some embodiments from about 7.5 to about25, and in some embodiments, from about 10 to about 20.

e. Viscosity Modifier

In addition, the emulsion can include one or more viscosity modifierswhich can also help to prevent the separation of the various componentsof the emulsion. For instance, in some embodiments, the one or moreviscosity modifiers can be added to the oil phase or the water phase ofan emulsion to adjust the viscosity such that separate components in theemulsion are more miscible. Further, the viscosity of the overallemulsion can be adjusted so that it is not so high that the emulsioncannot be sprayed onto a surface, but it is not so low that the emulsionis too runny such that it does not evenly coat the surface. As such, theemulsion can have a viscosity ranging from about 500 centipoise to about10,000 centipoise, such as from about 1000 centipoise to about 8000centipoise, such as from about 1500 centipoise to about 6000 centipoise,such as from about 2000 centipoise to about 4000 centipoise.

When a water-in-oil emulsion or an oil-in-water emulsion is formed, theone or more viscosity modifiers can be added to the water phase of thewater-in-oil emulsion or the oil-in-water emulsion to enhance themiscibility between the water phase and the oil phase, which promotesthe substantially homogeneous distribution of the components of thesprayable emulsion. It is also to be understood, however, that theviscosity modifier can be added to an already-formed oil-in-water orwater-in-oil emulsion to adjust the viscosity as needed.

Suitable viscosity modifiers include carboxylic acid polymers which arecrosslinked compounds containing one or more monomers derived fromacrylic acid, substituted acrylic acids, and salts and derivatives ofthese acrylic acids and substituted acrylic acids. They can becrosslinked homopolymers of an acrylic acid or of a derivative thereof,such as acrylamidopropylsulfonic acid. They can be also crosslinkedcopolymers having (i) a first monomer selected from the group consistingof (meth)acrylic acid, derivatives thereof, short chain (i.e., C₁-C₄)acrylate ester monomers, and mixtures thereof, and (ii) a second monomerwhich is a long chain (i.e., C₈-C₄₀) substituted polyethylene glycolacrylate ester monomer.

Examples of commercially available carboxylic acid polymers includeCARBOPOL™ 1342, PEMULEN™ TR-1, and PEMULEN™ TR-2 available from LubrizolCorp.; Sepigel 305, SIMULGEL™ EG, SIMULGEL™ NS, and SIMULGEL™ 600,available from Seppic S.A.; VISCOLAM™ AT100P and VISCOLAM™ AT64/P,available from Lamberti S.p.A. One commercially available viscositymodifier is available from Seppic S.A. as SIMULGEL™ NS. SIMULGEL™ NSincludes a hydroxylethyl acrylate/sodium acryloyldimethyl tauratecopolymer, squalane, and polysorbate 60, which can be added to an oilphase of a water-in-oil or oil-in-water emulsion.

Other suitable viscosity modifiers that can be used include cornstarch(topical starch), talc, rice starch, oat starch, tapioca starch, potatostarch, legume starches, soy starch, turnip starch, microcrystallinecellulose, kaolin, aluminum starch octenyl succinate, and mixturesthereof. Water soluble aluminum starch octenyl succinates arecommercially available from National Starch & Chemical Co. as DRY FLO™Pure, DRY FLO™ XT, DRY FLO™ PC, and/or DRY FLO™ AF (aluminum free grade)and are water soluble such that they can be included in a water phase ofa water-in-oil emulsion or an oil-in-water emulsion.

Regardless of the particular viscosity modifiers utilized, the viscositymodifier can be present in the sprayable emulsion in an amount rangingfrom about 0.05 wt. % to about 15 wt. %, such as from about 0.1 wt. % toabout 10 wt. %, such as from about 0.5 wt. % to about 5 wt. % based onthe total weight of the sprayable emulsion.

f. Conditioning Agents

The sprayable emulsion can further include one or more conditioningagents to help condition the skin. For example, the sprayable emulsioncan include thymol iodide, sodium chloride, magnesium dichloride,magnesium sulfate, lanolin, lanolin oil, lanolin wax, lanolin alcohols,lanolin fatty acids, isopropyl lanolate, ethoxylated lanolin,ethoxylated lanolin alcohols, ethoxylated cholesterol, propoxylatedlanolin alcohols, acetylated lanolin alcohols, lanolin alcoholslinoleate, lanolin alcohols ricinoleate, acetate of lanolin alcohols,ricinoleate, acetate of ethoxylated alcohols-esters, hydrogenolysis oflanolin, ethoxylated hydrogenated lanolin, ethoxylated sorbitol lanolin,or a combination thereof. Thymol iodide and magnesium sulfate may beparticularly useful. One or more conditioning agents can be present inthe sprayable emulsion in an amount ranging from about 0.05 wt. % toabout 10 wt. %, such as from about 0.1 wt. % to about 7.5 wt. %, such asfrom about 0.5 wt. % to about 5 wt % based on the total weight of theemulsion.

g. Additional Component

Other optional components in the sprayable emulsion can include skincare-additives such as emollients, as well as fragrances andpreservatives. For instance, an emollient such as caprylic/caprictriglyceride can be included in the sprayable emulsion. Other suitableemollients include stearoxy trimethyl silane, cetyl lactate, and alkyllactate, such as C₁₂-C₁₅ alkyl lactate. When emollients are used, thesprayable emulsion can feel smooth to the touch when applied to theskin. One or more emollients can be present in the sprayable emulsion inan amount ranging from about 0.1 wt. % to about 25 wt. %, such as fromabout 0.5 wt. % to about 20 wt. %, such as from about 1 wt. % to about15 wt. % based on the total weight of the sprayable emulsion.

Further, a fragrance can be present in the sprayable emulsion in anamount ranging from about 0.005 wt. % to about 2 wt. %, such as fromabout 0.01 wt. % to about 1.5 wt. %, such as from about 0.02 wt. % toabout 1 wt. % based on the total weight of the sprayable emulsion.

Meanwhile, preservatives can be present in the sprayable emulsion in anamount ranging from about 0.01 wt. % to about 6 wt. %, such as fromabout 0.02 wt. % to about 4 wt. %, such as from about 0.05 wt. % toabout 1 wt. % based on the total weight of the emulsion. Suitablepreservatives include paraben-based preservatives such as methylparabenand propylparaben.

In addition, the present inventors have found that a freezing pointdepressant can be included in the emulsion to limit the amount ofcrystallization of any solid components, which can then reduce or limitclogging of the emulsion when sprayed. If desired, one or more freezingpoint depressants may be employed, such as glycols (e.g., ethyleneglycol, propylene glycol, butylene glycol, triethylene glycol, hexyleneglycol, polyethylene glycols, ethoxydiglycol, dipropyleneglycol, etc.);glycol ethers (e.g., methyl glycol ether, ethyl glycol ether, isopropylglycol ether, etc.); and so forth. Such freezing point depressants canbe present in the emulsion in an amount ranging from about 0.1 wt. % toabout 15 wt. %, such as from about 0.5 wt % to about 10 wt. %, such asfrom about 1 wt. % to about 5 wt. % based on the total weight of theemulsion.

II. Formation of the Sprayable Emulsion

Generally, the sprayable emulsion of the present invention can be madeby forming a base emulsion, then introducing the base emulsioncomposition into a spray container, followed by injecting a propellantinto the container. When the base emulsion composition is in the form ofa water-in-oil emulsion or an oil-in-water emulsion, for example, thebase emulsion composition can be made by first separately forming an oilphase and a water phase.

The manner in which the emulsion is formed may vary as is known to thoseskilled in the art. In one embodiment, for example, an oil phase isformed by blending one or more oils with one or more components of theemulsification system described above. However, it is also be understoodthat one or more of the components of the emulsification system can beadded to the water phase in another embodiment. Emollients, conditioningagents, etc. also be added to form the oil phase. In such embodiments,the oil phase can contain oils in an amount of from about 30 wt. % toabout 80 wt. %, such as from about 35 wt. % to about 70 wt. %, such asfrom about 40 wt. % to about 60 wt. % based on the total weight of theoil phase. Further, the oil phase can include emulsifiers in an amountranging from about 5 wt. % to about 35 wt. %, such as from about 10 wt.% to about 30 wt. %, such as from about 15 wt. % to about 25 wt. % basedon the total weight of the oil phase. The addition of the emulsifierscan result in an oil phase having an HLB value between about 6 and about7. In addition, the oil phase can include emollients in an amountranging from about 10 wt. % to about 45 wt. %, such as from about 15 wt.% to about 40 wt. %, such as from about 20 wt. % to about 35 wt. % basedon the total weight of the oil phase. Moreover, the oil phase caninclude conditioning agents in an amount ranging from about 0.5 wt. % toabout 10 wt. %, such as from about 1 wt. % to about 7.5 wt. %, such asfrom about 1.5 wt. % to about 5 wt. % based on the total weight of theoil phase.

Meanwhile, the water phase can be formed by blending water and any watersoluble components of the sprayable emulsion, such as conditioningagents, viscosity modifiers, emulsifiers, etc. However, it is also to beunderstood that the water phase may include only water in otherembodiments. As such, the water phase can include water in an amountranging from about 50 wt. % to about 100 wt. %, such as from about 55wt. % to about 99 wt. %, such as from about 60 wt. % to about 98 wt. %.The water phase can also include conditioning agents in an amountranging from about 0.5 wt. % to about 15 wt. %, such as from about 1 wt.% to about 10 wt. %, such as from about 1.5 wt. % to about 7.5 wt. %based on the total weight of the water phase. Additionally, the waterphase can include viscosity modifiers in an amount ranging from about0.25 wt. % to about 10 wt. %, such as from about 0.5 wt. % to about 7.5wt. %, such as from about 1 wt. % to about 5 wt. % based on the totalweight of the water phase.

After the oil phase and water phase are separately formed, the waterphase can be added to the oil phase to form a water-in-oil emulsion. Thecombination of the phases may be facilitated through agitation (e.g.,stirring) and control of the temperatures of each mixture. Next, theactive agent particles can be added to the water-in-oil emulsion. Theactive agent particles can be present in the water-in-oil emulsion in anamount ranging from about 0.25 wt. % to about 35 wt. %, such as fromabout 0.5 wt. % to about 30 wt. %, such as from about 1 wt. % to about25 wt. %, such as from about 5 wt. % to about 15 wt. % based on thetotal weight of the base emulsion composition.

Then, if desired, other components such as fragrances, preservatives,freezing point depressants, and additional viscosity modifiers can beadded to the emulsion. Fragrances can be added in an amount ranging fromabout 0.01 wt. % to about 5 wt. %, such as from about 0.05 wt. % toabout 2.5 wt. %, such as from about 0.1 wt. % to about 1 wt. % based onthe total weight of the base emulsion composition. Likewise,preservatives can be added in an amount ranging from about 0.01 wt. % toabout 5 wt. %, such as from about 0.05 wt. % to about 2.5 wt. %, such asfrom about 0.1 wt. % to about 1 wt. % based on the total weight of thebase emulsion composition. In addition, freezing point depressants canbe added in an amount ranging from about 0.5 wt. % to about 15 wt. %,such as from about 1 wt. % to about 10 wt. %, such as from about 2 wt. %to about 8 wt. % based on the total weight of the base emulsioncomposition. Further, viscosity modifiers can be added in an amountranging from about 0.1 wt. % to about 15 wt. %, such as from about 0.5wt. % to about 10 wt. %, such as from about 1 wt. % to about 8 wt. %based on the total weight of the base emulsion composition. As such, itis to be understood that in some embodiments, a first viscosity modifiercan be added during formation of the water phase, while a secondviscosity modifier can be added after forming the emulsion by combiningthe water and oil phases to form the base emulsion composition.

Regardless of which phase is being formed, the temperature can rangefrom about 15° C. to about 40° C., such as from about 18° C. to about35° C., such as from about 20° C. to about 30° C. After the separatephases are mixed as described above, the resulting base emulsioncomposition can then be filled into a spray container, such as anaerosol spray container. The container can then be sealed, after whichthe propellant can be introduced into the container, such as via avalve. The container can be filled with the propellant at a pressureranging from about 130 psi to about 230 psi, such as from about 140 psito about 220 psi, such as from about 150 psi to about 210 psi.

III. Spray Delivery System

Various aerosol spray containers can be used in conjunction with thesprayable emulsion to form a system for spraying the emulsion onto asurface such as skin. One embodiment of a spray delivery systemcontemplated by the present invention is described with reference toFIG. 1. The spray delivery system 100 can include a spray container 101formed of metal or reinforced plastic. The spray container 101 has anupper opening into which a spray head 102 is fitted. The spray head or102 is fixed onto the spray container 101 in such a manner that a flange104 of the spray head is connected to a collar 103 formed around theedge of the upper opening in the spray container 101 by welding or otherpossible joining methods. This results in an airtight connection betweenthe spray head 102 and spray container 101.

The spray head 102 is provided with a valve 105 that is retained by theflange 104. The valve 105 is kept closed in its normal condition by theenergizing force of a spring 106, but it opens when the spray head 102is pressed. The spray head 102 further has a spray nozzle 107 whichcommunicates with the valve 105 through a conduit pipe 108. Meanwhile, adip tube 109 is connected to the valve 105 and extends to the bottom ofthe spray container 101. By pressing the spray head 102 downwardlyagainst the spring 106, the valve 105 opens to form a fluid passage fromthe lower end port of the dip tube 109 to the spray nozzle 107 throughthe valve 105 and conduit pipe 108.

A sprayable emulsion 110, formed as discussed above, can be charged intothe spray container 101. Then, by pressing the spray head 102, thesprayable emulsion is discharged in the form of a fine mist from thespray nozzle 107 through the aforementioned fluid passage by thepressure associated with the propellant that is substantiallyhomogeneously dispersed in the sprayable emulsion 110.

Another embodiment of a spray delivery system is described withreference to FIGS. 2A, 2B, 3 and 4. Because of the use of active agentparticles, it is possible that the sprayable emulsion could clog somespray delivery systems. For instance, standard aerosol spray deliverysystems often utilize an actuator (spray button) not intended fordelivering compositions containing high concentrations of particulatematerial such as the active agent particles of the present invention.Such actuators often utilize a mechanical break-up insert to finelyatomize sprayable emulsions containing low levels of particulates. Forinstance, the actuators can contain small channels to cause a swirlingeffect, resulting in a fine mist spray. However, when sprayablecompositions and emulsions containing higher amounts of active agentparticles are utilized, the active agent particles or any otherparticles can clog the actuator and prevent an even spray from thecontainer. As such, the spray delivery system of the present inventionrepresented by FIGS. 2A, 2B, 3 and 4 does not include the aforementionedactuator channels and is free from a mechanical break-up insert.Instead, the spray delivery system utilizes a valve and stem systemwhere the stem design allows for automatic wiping of the stem inside thevalve as the valve is sprayed, which prevents the buildup of solidsinside the valve, thus minimizing the risk of clogging. In addition, thevalve includes a valve orifice having a diameter that is large enoughsuch that the active agent particles and other particles of thesprayable emulsion do not clog inside the container and such that aneven mist can be achieved. Further, the valve includes a vapor tap toallow for enhanced blending of the propellant vapor during spraying andto prevent the buildup of particles inside the valve. The addition ofthe vapor tap also results in a more uniform delivery of the sprayableemulsion from the delivery system. The vapor tap also allows for anincreased weight percentage of propellant to be utilized, which helps tocreate a drier, less runny product when delivered to the surface of theskin. Further, the vapor tap creates a spray that feels warmer becauseit helps to volatilize the propellant and solvents before the emulsionreaches the surface of the skin.

The spray system is discussed in more detail below in reference to FIGS.2A, 2B, 3, and 4. FIG. 2A shows a front view of a non-mechanical breakupactuator 200 that can be used in a spray delivery system according toone embodiment of the present disclosure. The actuator 200 is acomponent that can be used to depress a stem component of a valveassembly to initiate introduction of the sprayable emulsion, as isdiscussed in more detail below in reference to FIGS. 3 and 4. Theactuator 200 includes a locking ring 201, an insert 202, and a dome 203.The locking ring 201 keeps the actuator from being depressedinadvertently. The actuator dome 203 can contain the insert 202, and theinsert 202 can determine the spray characteristics of the sprayableemulsion. The insert 202 of FIGS. 2A and 2B is a non-mechanical breakupinsert. The insert 202 defines an opening 204 from which the sprayableemulsion of the present invention can exit the actuator, and the openingis hereinafter referred to as the actuator orifice or exit orifice 204.The exit orifice 204 can have a diameter selected based on the particlesize of the particulate components in the sprayable emulsion, such asthe active agent particles, so that the particles and other componentsof the sprayable emulsion can be sprayed from the exit orifice 204without causing clogging of the spray delivery system. Further, byselectively controlling the diameter of the exit orifice 204, the sizeof the resulting spray pattern can also be influenced. For instance, toosmall of a diameter can result in a very narrow spray pattern, while toolarge of a diameter can result in a spray pattern that is too wide,resulting in overspray into the surrounding environment other than thesurface to be sprayed, such as clothing, bedding, etc.

For instance, the exit orifice 204 can have a diameter ranging fromabout 0.3 millimeters to about 0.6 millimeters, such as from about 0.35millimeters to about 0.55 millimeters, such as from about 0.4millimeters to about 0.5 millimeters. FIG. 2B is a cross-sectional sideview of the actuator of FIG. 2A, which shows the arrangement of the exitorifice 204 in relation to the insert 202 positioned inside the dome203. The exit orifice is connected to a stem 302 of a valve assembly viaan exit path 205, which is discussed in more detail in FIG. 3.

Turning now to FIGS. 3 and 4, a cross-sectional side view of a spraydelivery system that includes a spray valve assembly 300 and mountingcup 301 that can be used in conjunction with the actuator 200 of FIGS.2A and 2B is shown. The actuator 200 is connected to the valve assembly300 by exit path 205 as shown in FIG. 2B. The spray valve assembly 300includes a housing or body 305 that holds the stem 302, a stem gasket304, and a spring 307. A dip tube 311 is also attached to the housing305 via a tail pipe 309. The mounting cup 301 holds the spray valveassembly 300 together and can be crimped onto a container 401 to providea seal. Generally, when the actuator 203 (see FIGS. 2A and 2B), which isdisposed above the mounting cup 301, is depressed against the spring307, the stem 302 of the valve assembly 300 moves downward, opening theseal between the stem gasket 303 and stem 302, such that a stem orifice303 in the stem 302 passes below the stem gasket 304. This results inthe propellant component of the sprayable emulsion forcing the baseemulsion composition up the dip tube 311 through a tailpipe orifice 310,into the valve body 305. A vapor tap 306 formed in the valve body 305supplies additional propellant to the valve body 305 and helps to mixthe liquid base emulsion composition and propellant in the valve body305, which can result in a more homogeneous distribution and reduce therisk of clogging of any active agent particles. The vapor tap 306 alsokeeps the base emulsion composition out of the valve body 305 when atrest due to the vapor pushing the base emulsion composition down, andalso functions to prevent product settling. Once the sprayable emulsion(i.e., the substantially homogeneously blended propellant and baseemulsion composition) reaches the stem through the stem orifice 303, itthen passes through the exit path 205, and out the exit orifice 204 as afine mist that does not clog the spray delivery system 400.

The dimensions of the various components can be selected to furtherminimize the risk of clogging. For instance, the stem 302 can have adiameter of from about 3 millimeters to about 5.5 millimeters, such asfrom about 3.5 millimeters to about 5 millimeters, such as from about 4millimeters to about 4.5 millimeters. Meanwhile, the stem orifice 303can have a diameter of from about 0.5 millimeters to about 0.75millimeters, such as from about 0.55 millimeters to about 0.7millimeters, such as from about 0.6 millimeters to about 0.65millimeters. Additionally, the tailpiece orifice 310 can have a diameterof from about 0.75 millimeters to about 2 millimeters, such as fromabout 1 millimeter to about 1.75 millimeters, such as from about 1.25millimeters to about 1.5 millimeters. Further, the vapor tap 306 canhave a diameter of from about 0.1 millimeters to about 0.5 millimeters,such as from about 0.15 millimeters to about 0.45 millimeters, such asfrom about 0.2 millimeters to about 0.4 millimeters. By selectivelycontrolling the aforementioned dimensions, the propellant of thesprayable emulsion can remain substantially homogeneously distributedthroughout the emulsion to reduce settling of the active agentparticles, and the sprayable emulsion can leave the exit orifice 204 asa fine mist with less fly away and can be more evenly distributed thanwhen, for instance, a mechanical actuator is utilized.

IV. Application of the Sprayable Emulsion

As a result of the combination of the type of spray delivery systemutilized and the characteristics of the sprayable emulsion, asubstantially uniform coating of the emulsion can be applied to asurface. For instance, the emulsion of the present invention can beapplied to a surface of the skin for the treatment of various skinconditions or irritations such as diaper rash; dry skin; ulcers;superficial cuts, scrapes, wounds, and first degree burns; etc. Areas ofskin that can be treated include the buttocks, particularly in the caseof diaper rash/incontinent dermatitis, as well as the arms, elbows,hands, abdomen, back, sacrum, coccyx, hips, knees, feet, ankles, heels,etc. As the emulsion reaches the skin's surface, the propellant canevaporate, leaving a substantially uniform coating of the active agentparticles on the skin. Further, the active agent particles can bedistributed throughout the coating in a substantially uniform manner.After the emulsion has been sprayed onto the skin in the form of asubstantially uniform coating, the amount of active agent particlespresent in the emulsion on the skin can range from about 0.25 wt. % toabout 35 wt. %, such as from about 0.5 wt. % to about 30 wt. %, such asfrom about 1 wt. % to about 25 wt. %, such as from about 5 wt. % toabout 15 wt. % based on the total weight of the resultant coating (e.g.,the sprayable emulsion excluding the evaporated components such as thepropellant).

The present invention may be better understood by reference to thefollowing examples.

Example 1

A sprayable emulsion was formed from a base emulsion compositionincluding a preservative phase, an oil phase, a water phase, and activeagent particles, to which a propellant was added. First, to make thepreservative phase of the base emulsion composition, a freezing pointdepressant was added to a beaker and agitated with a propeller. Next,preservatives were added to the beaker and mixing was initiated using astirrer equipped with an anchor-type sidewipe agitator. Agitation wascontinued for at least 15 minutes until the solution was completelydissolved. The preservative phase was then set aside.

Next, to make the oil phase of the base emulsion composition, emollientswere added to a separate beaker and agitated with a propeller toinitiate mixing while maintaining a temperature between 20° C. and 23°C., after which the polyglyceryl-4 isostearate/cetyl dimethiconecopolyol/hexyl laurate emulsifier was added, followed by the cetylPEG/PPG-10/1 dimethicone emulsifier, the sorbitan oleate emulsifier, thepolysorbate 80 emulsifier, and the octyldodecanol/octyldechylxyloside/PEG-30 emulsifier. Mixing via agitation was continued, whilemaintaining a temperature between 20° C. and 25° C. Next, the siliconeoil was added to the beaker, while maintaining a temperature between 20°C. and 23° C. A homogenizer was then used for agitation, using coolingwater to maintain a temperature between 20° C. and 25° C., after which aconditioning agent was added. Agitation was continued for at least 15minutes until the solution was completely dissolved, maintaining atemperature between 20° C. and 28° C. The resulting oil phase of thebase emulsion composition had an HLB value between 6 and 7.

Next, the water phase of the base emulsion composition was prepared in aseparate beaker. Water was added to the beaker while maintaining atemperature between 20° C. and 28° C. Mixing was initiated using astirrer equipped with a stainless steel three propeller blade. Awater-soluble conditioning agent was added to the beaker and mixing wascontinued for at least 15 minutes until all solids were dissolved. Then,the viscosity modifier containing hydroxyethyl acrylate/sodiumacryloyldimethyl taurate copolymer, squalane, and polysorbate 60 wasadded to the beaker, and mixing was continued for at least 15 minutes.

To prepare the base emulsion composition, the oil phase beaker wasmaintained at a temperature between 20° C. and 25° C. The water phasewas then slowly transferred to the oil phase beaker under homogenizeragitation, where the transfer time was at least 20 minutes. Thehomogenizer speed was increased as needed, while maintaining atemperature between 20° C. and 25° C. The resulting water-in-oilemulsion was then covered and mixed for at least 30 minutes. Thepreservative phase was then added to the beaker while continuing mixingfor at least 15 minutes and maintaining a temperature of from 20° C. to25° C. After ensuring that all powders were off the surface andincreasing the mixing speed as needed, zinc oxide particles were addedunder homogenizer agitation and mixed for at least 5 minutes, increasingthe speed as needed and maintaining a temperature of from 20° C. to 25°C. Then the viscosity modifier aluminum starch octenylsuccinate wasadded under homogenizer agitation and mixed for at least 5 minutes,increasing the speed as needed and maintaining a temperature of from 20°C. to 25° C. Thereafter, fragrance was added to the beaker underhomogenizer agitation, and the emulsion was mixed for at least 15minutes. The resulting base emulsion composition had an HLB value of7.42.

After the base emulsion composition was formed, it was filled into anaerosol spray container, after which the container's valve was sealed orcrimped to the top of the container. Then, HFO-1234ze propellant waspressure filled via the valve into the container at a pressure of about200 pounds. The resulting sprayable emulsion included a substantiallyhomogeneous blend of the propellant and active agent particles, andcontained 22 wt. % of the propellant and 78 wt. % of the base emulsioncomposition. The sprayable emulsion had a specific gravity of about1.045. The weight percentages of the components used in the sprayableemulsion are summarized below in Table 1. Once sprayed on a surface(e.g., skin) as a substantially uniform coating, the emulsion contained10.4 wt. % of zinc oxide particles due to evaporation of the propellant.

TABLE 1 Sprayable Emulsion Components Sprayable Emulsion Component Wt. %HFO-1234ze 22.00 Zinc Oxide Particles 8.11 Polyglyceryl-4 Isostearate;Cetyl PEG/PPG-10/1 0.98 Dimethicone; Hexyl Laurate Cetyl PEG/PPG-10/1Dimethicone 0.98 Sorbitan Oleate 0.43 Polysorbate 80 0.35Octyldodecanol/Octyldodecyl Xyloside/PEG-30 3.12 DipolyhydroxystearateAluminum Starch Octenylsuccinate 2.34 Hydroxyethyl Acrylate/SodiumAcryloyldimethyl 0.78 Taurate Copolymer, Squalane, Polysorbate 60Silicone Oil 15.60 Water 29.76 Conditioning Agents 1.95 Fragrance 0.16Freezing Point Depressant 3.12 Preservatives 0.20 Emollients 10.14 Total100.00

These and other modifications and variations of the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged both in whole or in part. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention so further described in such appended claims.

What is claimed is:
 1. A sprayable emulsion comprising ahydrofluoro-based propellant, an emulsification system, an oil phase, awater phase, and active agent particles, wherein the emulsificationsystem comprises at least one nonionic emulsifier, wherein the emulsionhas a viscosity ranging from about 500 centipoise to about 10,000centipoise and a hydrophilic to lipophilic balance (HLB) value of fromabout 2 to about
 12. 2. The sprayable emulsion of claim 1, wherein theemulsification system comprises one or more nonionic lipophilicemulsifiers and one or more nonionic hydrophilic emulsifiers, whereinthe weight ratio of the nonionic lipophilic emulsifiers to the nonionichydrophilic emulsifiers ranges from about 5 to about
 30. 3. Thesprayable emulsion of claim 2, wherein the nonionic lipophilicemulsifier comprises a non-crosslinked dimethicone polyol, a sorbitanfatty acid ester, an octyldodecanol, or a combination thereof.
 4. Thesprayable emulsion of claim 2, wherein the nonionic hydrophilicemulsifier comprises a sorbitan fatty acid ester modified with apolyoxymethylene.
 5. The sprayable emulsion of claim 1, wherein thepropellant is homogeneously distributed throughout the emulsion.
 6. Thesprayable emulsion of claim 1, wherein the active agent particles arehomogeneously distributed throughout the emulsion.
 7. The sprayableemulsion of claim 1, wherein the propellant is present in an amountranging from about 5 wt. % to about 95 wt. % and the active agentparticles are present in an amount ranging from about 0.5 wt. % to about30 wt. % based on the total weight of the emulsion.
 8. The sprayableemulsion of claim 1, wherein the emulsion is a water-in-oil emulsion. 9.The sprayable emulsion of claim 1, wherein the oil phase comprises fromabout 1 wt. % to about 35 wt. % and the water phase comprises from about1 wt. % to about 50 wt. % of the total weight of the emulsion.
 10. Thesprayable emulsion of claim 1, wherein the oil phase comprises asilicone oil.
 11. The sprayable emulsion of claim 1, wherein the waterphase comprises water.
 12. The sprayable emulsion of claim 1, whereinwater is present in an amount of less than about 50 wt. % based on thetotal weight of the emulsion.
 13. The sprayable emulsion of claim 1,wherein the emulsion further comprises a viscosity modifier.
 14. Thesprayable emulsion of claim 13, wherein the viscosity modifier comprisesa carboxylic acid polymer, a starch, or a combination thereof.
 15. Thesprayable emulsion of claim 1, wherein less than about 3 wt. % of theactive agent particles in the emulsion settle when the emulsion isstored in a container at about 21° C. for 3 days.
 16. The sprayableemulsion of claim 1, wherein the propellant has a first specific gravityand the sprayable emulsion has a second specific gravity, wherein theratio of the first specific gravity to the second specific gravity isfrom about 0.7 to about 1.6.
 17. The sprayable emulsion of claim 1,wherein the propellant has a vapor pressure of less than about 60 psi atabout 21° C.
 18. The sprayable emulsion of claim 1, wherein thepropellant comprises a hydrofluoro-olefin or a hydrofluoroalkane. 19.The sprayable emulsion of claim 1, wherein the active agent particlescomprise a moisture barrier, antifungal, antibacterial, analgesic,antiseptics, anesthetic, anti-inflammatory, antipruritic, or acombination thereof.
 20. The sprayable emulsion of claim 1, wherein theemulsion further comprises one or more emollients, conditioning agents,freezing point depressants, preservatives, or a combination thereof. 21.A method of forming a sprayable emulsion comprising: forming a baseemulsion composition, wherein the base emulsion composition comprisesactive agent particles, an emulsification system, an oil phase, and awater phase, wherein the emulsification system comprises at least onenonionic emulsifier; introducing the base emulsion composition into aspray container; and injecting a hydrofluoro-based propellant into thecontainer, wherein the sprayable emulsion has a viscosity of from about500 centipoise to about 10,000 centipoise and a hydrophilic tolipophilic balance (HLB) value of from about 2 to about
 12. 22. Themethod of claim 21, wherein the emulsification system comprises at leastone nonionic lipophilic emulsifier and at least one nonionic hydrophilicemulsifier.
 23. The method of claim 22, wherein the weight ratio of thenonionic lipophilic emulsifiers to the nonionic hydrophilic emulsifiersranges from about 5 to about
 30. 24. The method of claim 22, wherein thenonionic lipophilic emulsifier comprises a non-crosslinked dimethiconepolyol, a sorbitan fatty acid ester, an octyldodecanol, or a combinationthereof.
 25. The method of claim 22, wherein the nonionic hydrophilicemulsifier comprises a sorbitan fatty acid ester modified with apolyoxymethylene.
 26. The method of claim 21, wherein the emulsificationsystem is added to the oil phase.
 27. The method of claim 21, whereinthe base emulsion system further comprises a viscosity modifier.
 28. Themethod of claim 27, wherein the viscosity modifier comprises acarboxylic acid polymer, a starch, or a combination thereof.
 29. Themethod of claim 27, wherein the viscosity modifier is added to the waterphase.
 30. The method of claim 21, wherein the active agent particlesare substantially homogeneously dispersed throughout the sprayableemulsion.
 31. The method of claim 21, wherein the propellant issubstantially homogeneously dispersed throughout the sprayable emulsion.32. The method of claim 21, further comprising adding one or morepreservatives, emollients, skin conditioners, freezing pointdepressants, or a combination thereof to the emulsion.
 33. The method ofclaim 21, wherein the propellant has a first specific gravity and thesprayable emulsion has a second specific gravity, wherein the ratio ofthe first specific gravity to the second specific gravity is from about0.7 to about 1.6.
 34. The method of claim 21, wherein the sprayableemulsion is formed at a temperature ranging from about 15° C. to about40° C.